Stripping absorption module

ABSTRACT

In a process, a portion of a liquid mixture flow is vaporized to produce a vapor and a depleted flow of liquid. The vapor is introduced to a brine which is adapted to exothermically absorb one or more components therefrom, and heat is withdrawn, to produce at least a flow of heat and a flow of brine which is enriched in the one or more components. The heat previously withdrawn is transferred, to drive the vaporization. This transfer can be associated with the change of a working fluid from a gaseous into a liquid gate. In this case, the heat withdrawal involves the change of the working fluid from the liquid to the gaseous state. In the liquid state, the working thud flows only by one or more of gravity, convection and wicking. In the gaseous state, the working fluid flows only by one or more of diffusion and convection.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application is a Division of application Ser. No. 14/078,105 filedon Nov. 12, 2013. Application Ser. No. 14/078,105 is a Continuation ofapplication Ser. No. 12/906,197 filed on Oct. 18, 2010. Application Ser.No. 12/906,197 claims the benefit of U.S. Provisional Application61/381,333 filed on Sep. 9, 2010, application Ser. No 12/906,197 is aContinuation-in-part of Application PCT/CA2010/000604 filed on Apr. 16,2010. Application PCT/CA2010/000604 claims the benefit of U.S.Provisional Application 61/313,156 filed on Mar. 12, 2010. ApplicationPCT/CA2010/000604 claims the benefit of U.S. Provisional Application61/231,412 filed on Aug. 5, 2009, Application PCT/CA2010/000604 claimspriority for Application 2,663,397 filed on Apr. 20, 2009 in Canada.

FIELD OF THE INVENTION

The present invention relates generally to the field of fluidseparation.

BACKGROUND OF THE INVENTION

In the field of fluid separation, it is known to utilize a brine, suchas a LiBr brine, for the absorption of a process vapor and theconsequential generation of heat. It is also known to utilize a pump todrive a heat-carrying fluid around a heat exchange circuit to carry theheat generated by the absorber to an evaporator or boiler to produce theprocess vapor.

SUMMARY OF THE INVENTION

A process for use with a flow of a liquid mixture that is separable byvaporization into a flow of vapor and a depleted flow of liquid formsone aspect of the invention. The process comprises: a vaporization step,wherein a portion of said liquid mixture flow is vaporized to producesaid flow of vapor and said depleted flow of liquid; an absorption step,wherein (i) the flow of vapor is introduced to a flow of brine which isadapted to exothermically absorb one or more components from the vaporand (ii) heat is withdrawn, to produce at least a flow of heat and aflow of brine which is enriched in the one or mare components; and aheat transfer step, wherein the heat withdrawn in the absorption step istransferred, to drive the vaporization in the vaporization step. Thetransfer of heat to drive the vaporization is associated with the phasechange of a working fluid from a gaseous state into a liquid state. Thewithdrawal of heat in the absorption step involves the phase change ofthe working fluid from the liquid state into the gaseous state. In theliquid state, the working fluid flows only by one or more of gravity,convection and wicking.

In the gaseous state, the working fluid flows only by one or more ofdiffusion and convection.

Apparatus forms another aspect of the invention. The apparatus is foruse with a flow of a liquid mixture that is separable by vaporizationinto a flow of vapor and a depleted flow of liquid. The apparatuscomprises a structure which, in use;

-   -   defines a first volume wherein said liquid mixture is received        and separated into said flow of vapor and said depleted flow of        liquid;    -   defines a first liquid passage by which said depleted flow        leaves the first volume;    -   defines a vapor passage by which said flow of vapor leaves the        first volume;    -   defines a second volume to which the vapor passage leads;    -   includes heat and mass transfer apparatus disposed at least in        part in the second volume, the heat and mass transfer        apparatus; (i) receiving a flow of brine adapted to        exothermically absorb one or more components from the        vapor; (ii) introducing the flow of brine to the vapor;        and (iii) withdrawing heat from the second volume, to produce at        least a flow of heat and a flow of brine which is enriched in        the one or more components;    -   defines a second liquid passage by which the flow of brine which        is enriched in the one or more components leaves the second        volume; and    -   includes heat movement apparatus for transferring the flow of        heat to the first volume to provide for said separation.

In the apparatus, in use, the transfer of heat into the first volume isassociated with the phase change of a working fluid from a gaseous stateinto a liquid state; the withdrawal of the heat from the second volumeinvolves the phase change of the working fluid from the liquid state tothe gaseous state; in the liquid state, the working fluid flows only byone or more of gravity, convection and wicking; and in the gaseousstate, the working fluid flows only by one or more of diffusion andconvection.

According to another aspect of the invention, the heat movementapparatus and as of the heat and mass transfer apparatus can be definedby one or more heat pipes, each of said one or more heat pipes having aheat receiving part disposed in the second volume and a heat deliveringpart disposed in the first volume to provide for said heat transfer.

According to another aspect of the invention, the one or more heat pipescan be stacked such that that portion of the heat pipes disposed in thefirst volume operate in use as a packed vaporization column and thatportion of the heat pipes disposed in the second volume operate in useas a packed absorption column.

According to another aspect of the invention, in use, the vapor leavingthe first volume can be in substantial vapor-liquid equilibrium with theliquid mixture entering the first volume.

According to another aspect of the invention, in use, the temperature ofthe depleted flow of liquid leaving the first volume can be lower thanthe temperature of the liquid mixture entering the first volume.

According to another aspect of the invention, in use, the pressure inthe first volume and the temperature of the liquid mixture entering thefirst volume can be such that substantially all of the heat transferredto the first volume results in vaporization of the liquid mixture.

According to another aspect of the invention, the structure can furtherdefine a vent leading from the second volume; and in use, at least asubstantial portion of the vapor can be absorbed in the second volume,the balance leaving the second volume via the vent.

According to another aspect of the invention, the apparatus can furthercomprise desorption apparatus for receiving the flow of brine producedby the heat and mass transfer apparatus and producing; the flow of brineadapted to exothermically absorb said one or more components from thevapor; and a product stream.

According to another aspect of the invention, the apparatus can furthercomprise: a secondary absorber which, in use: (i) receives the balanceof the vapor; and (ii) introduces the balance of the vapor to asecondary flow of brine which is adapted to exothermically absorb theone or more components, to produce a diluted brine.

According to another aspect of the invention, the desorption apparatuscan further receive the diluted brine and further produces the secondaryflow of brine.

According to another aspect of the invention, in use: the pressures inthe first volume and second volume can be reduced in comparison toatmospheric pressure; at least the majority of the vapor can be absorbedin the second volume; and a vacuum pump can provide for at least thenon-condensables of the vapor to be voided from the apparatus.

According to another aspect of the invention, the first volume can bedefined by one or more first voids and the second volume can be definedby one or more second voids.

According to another aspect of the invention, each of the one or morefirst voids and each of the one or more second voids can be defined by arespective vessel; and piping can define the vapor passage.

According, to another aspect of the invention, each of the one or morefirst voids and each of the one or more second voids can be defined in avessel.

According to another aspect of the invention, piping exterior to thevessel can define the vapor passage.

According to another aspect of the invention: the vessel can becompartmentatilized by bulkheads to define the one or more first voidsand one or more second voids and; one or more apertures defined in thebulkheads can define the vapor passage.

The apparatus can form part of a bioproduct production facility, whichforms another aspect of the invention. The facility comprises, inaddition to the apparatus, an arrangement wherein, in use, catabolism ofa broth takes place on a continuous basis. The apparatus is coupled tothe arrangement to; withdraw a flow of the broth on a continuous basis;remove a catabolic inhibitor from the withdrawn broth to produce aninhibitor-containing flow and a remainder flow; and return the remainderflow to the arrangement.

According to another aspect of the invention, the catabolism can befermentation and the inhibitor can be alcohol.

According to another aspect of the invention, the inhibitor-containingflow can have a higher concentration of the inhibitor than does thebroth.

According to another aspect of the invention, in use, a bleed stream ofthe broth can be withdrawn to avoid toxin buildup; the bleed stream canbe fermented in batches; and the facility can further comprise furtherapparatus for receiving the product of a batch fermentation andproducing (i) a stream of whole stillage from which ethanol has beensubstantially removed and (ii) brine enriched in ethanol which is had tothe desorption apparatus and separated.

According to another aspect of the invention, in use; the brothwithdrawn from the arrangement can have a temperature of about 28-32° C.and an ethanol concentration of about 4-10%; the remainder flow can havea temperature of about 2-4° C. lower than that of the withdrawn flow,and have an ethanol concentration of about 2-6% less than that of thewithdrawn flow; and the pressure in the first volume can be about 30-100Torr.

According to another aspect of the invention, in use; the brothwithdrawn from the arrangement can have a temperature of about 30° C.and an ethanol concentration of about 7%; the remainder flow can have atemperature of about 28° C. and an ethanol concentration of about 2%;and the pressure in the first volume can be about 30 Torr.

According to another aspect of the invention, the heat pipes can bearranged parallel to a common axis and the structure can be adapted forpivotal movement about a horizontal axis which is orientated normally tothe common axis.

The apparatus of the invention can, according to yet another aspect ofthe invention, form part of a bio-product production facility whichcomprises an arrangement wherein, in use, catabolism of a broth takesplace on a batch basis. In this facility, the apparatus is coupled tothe arrangement to: withdraw a flow of the broth; remove a catabolicinhibitor from the withdrawn broth to produce an inhibitor-containingflow and a remainder flow; and return the remainder flow to thearrangement.

Other advantages, features and characteristics of the present inventionwill become more apparent upon consideration of the following detaileddescription and the appended drawings, the latter being brieflydescribed hereinafter, it being understood in the drawings, likereference numerals denote like structures throughout.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a stripping/absorption module according toan exemplary embodiment of the invention;

FIG. 2 is a schematic view of the module of FIG. 1 in an exemplary use;

FIG. 3 is a view, similar to FIG. 2, of another exemplary use of thestructure of FIG. 1;

FIG. 4 is a another schematic view showing another exemplary use of thestructure of FIG. 1;

FIG. 5 is a schematic view of an ethanol production facility employingtwo modules according to FIG. 1;

FIG. 6 is a simplified schematic view of the ethanol production facilityof FIG. 5 in combination with a simplified view of the structure of FIG.4;

FIG. 7 is a schematic view of an alternate embodiment of the module ofFIG. 1:

FIG. 8 is a schematic view of a yet further embodiment of the module ofFIG. 1;

FIG. 9 is a cross-sectional view of a yet further embodiment of themodule of FIG. 1; and

FIG. 10 is a schematic view of another embodiment of the invention.

DETAILED DESCRIPTION

A stripping/absorption module (SAM) is shown in FIG. 1 in schematic formand designated with general reference numeral 20.

This module comprises: a vessel 21, a pair of bulkheads 22,24, aplurality of heat pipes 24 and a pair of distributors 28,30.

Vessel 21 is a robust vessel, suitable for operation at reducedpressures, for example, 30 Torr.

The pair of bulkheads comprises a first bulkhead 22 and a secondbulkhead 24. The first bulkhead 22 extends upwardly from the base of thevessel and terminates beneath the top of the vessel. The second bulkhead24 is disposed in spaced relation from the first, extends downwardlyfrom the to of the vessel and terminates above the base. Through thisarrangement, first 32 and second 34 voids are defined interiorly of thevessel, which are coupled to one another by a conduit 35 defined by thespace between the bulkheads 22,24.

The vessel is punctuated by a plurality of ports 36-44, one lower port36,38 at the base of each void, one upper port 40,42 adjacent the top ofeach void and one uppermost port 44 proximal the top of the second void34.

The plurality of heat pipes 26 extend from the first void 32 to thesecond void 34 and are for carrying heat from the second void 34 to thefirst void 32. The heat pipes 26 are of conventional construction and assuch are not described herein in detail.

The pair of distributors 28,30 extend one each from the upper ports40,42 of the first and second voids 32, 34 and are adapted for wettingthe heat pipes 26.

From this, it should be understood that the major functional features ofthe illustrated SAM are:

-   -   first void 32;    -   second void 34;    -   the conduit 35 connecting the first and second voids;    -   the lower ports 36,38;    -   the upper ports 40,42;    -   the uppermost port 44;    -   the heat pipes 26; and    -   the distributors 28,30

FIG. 2, which is a schematic embodiment of an exemplary separatorapparatus for use with a flow of a mixed liquid that is separable byvaporization into a flow of vapor and a depleted flow of liquid, showsthe manner in which such major functional features operate in use.

Herein, it will be seen that the module 20 is shown along with asecondary absorber 46 and a desorption apparatus 48.

Turning first to the module 20, it will be understood that the firstvoid 32 forms a first volume. This is where the flow of mixed liquid isreceived and partially vaporized into the aforementioned flows of vaporand depleted flow of liquid. The manner in which vaporization is carriedout is described below, in the description relating to the heat pipes.

The lower port 42 at the base of the first volume defines a first liquidpassage by which said depleted flow of liquid leaves the first volume32.

The conduit 35 defines a vapor passage by which said flow of vaporleaves the first volume 32.

The second void 34 defines a second volume to which the vapor passage 35leads.

The uppermost port 44 defines a vent.

The distributors 28,30 and heat pipes 26 together define heat and masstransfer apparatus and heat movement apparatus. The heat and masstransfer apparatus: (i) receives flow of brine adapted to exothermicallyabsorb one or more components from the vapor; (ii) introduces the flowof brine to the vapor (i.e. the brine is sprayed or dropped into thesecond volume 34 onto the heat pipes 24); and (iii) withdraws heat fromthe second volume, to produce at least a flow of heat and a flow ofbrine which is enriched in the one or more components. The heat movementapparatus transfers the flow of heat to the first volume 32 to providefor said separation, and as such, each of the heat pipes 26 has a heatreceiving part disposed in the second volume and a heat delivering partdisposed in the first volume.

The brine can be, for example, only, LiBr solution having a lithiumbromide mass concentration between 40% to 70%, preferably between 45% to65%. However, any absorbent fluid known in the art would be suitable.

The lower port 38 at the base of the second volume 34 defines a secondliquid passage by which the flow of brine which is enriched in the oneor more components leaves the second volume 34.

By virtue of use of the heat pipes, it will be understood that: that thetransfer of heat into the first volume is associated with the phasechange of a working fluid, in this case, water, from a gaseous stateinto a liquid state; the withdrawal of the heat from the second volumeinvolves the vaporization of the working fluid from the liquid stateinto the gaseous state; the working fluid in the liquid state flows onlyby one or more of gravity and wicking; and the working fluid in thisgaseous state flows only by one or more of diffusion and convection.Working fluids other than water can and would be used depending upon theapplication: ammonia and commercial refrigerant fluids are but twoexamples. The choice of working fluid is a matter of routine to personsof ordinary skill and as such is not described herein.

The heat pipes 26 are stacked such that that portion of the heat pipesdisposed in the first volume 32 operate in use as a packed evaporationcolumn and that portion of the heat pipes disposed in the second volume34 operate in use as a packed absorption column.

Accordingly:

-   -   the vapor leaving the first volume 32 is in substantial        vapor-liquid equilibrium with the mixed liquid entering the        first volume 32;    -   at least a substantial portion of the vapor is absorbed in the        second volume 34, with the balance leaving the second volume via        the vent 44.

The secondary absorber 46: (i) receives the balance of the vapor, i.e.that portion not absorbed in the SAM; and (ii) introduces the balance ofthe vapor to a secondary flow of brine which is adapted toexothermically absorb the one or more components. This produces adiluted brine and also produces a gas stream composed of non-absorbablegases and any non-absorbed absorbables, the latter being vacated fromthe secondary absorber along arrow 50.

The desorption apparatus 48, i.e. a boiler or a distillation apparatus,receives the flow of brine produced by the heat and mass transferapparatus and the diluted brine produced by the secondary absorber 46and produces:

-   -   the flow of brine 52 adapted to exothermically absorb at least        one or more components from the vapor; and the secondary flow of        brine 54; and    -   a product stream 56.

FIG. 3 shows a variation of the structure of FIG. 2, for use incircumstances wherein the pressures in the first volume and secondvolume are reduced in comparison to atmospheric pressure, in thisapplication, at least the majority of the enriched vapor is absorbed inthe second volume and a vacuum pump 58 provides for the non-condensablesand any unabsorbed condensables in the vapor to be voided from theapparatus.

Turning now to FIG. 4, same will be understood to show in schematic forma plant that could be usefully used for concentrating apple juice. Thisplant is generally similar to the structure of FIG. 3, i.e. In that itincludes a SAM 20, a secondary absorber 46 and a vacuum pump 58, but thedesorption apparatus 48 has, rather than a distillation device, atwo-stage desorber [since the purpose in this application is not tofractionate the mixed liquid but merely to concentrate the juice.] Thetwo-stage desorber includes a number of economizers 60, toadvantageously pass heat between various parts of the process, a pair ofboilers 62 and variety of pumps 64. Predictions have been made inrespect of the operation of this system, the values being set forth onTable 1, below.

TABLE 1 Flow rate lb/hr Stream Water LiBr Total Temp ° C. % LiBr 1 100 0100 30 0 2 60 0 60 30 0 3 40 0 40 30 0    4A 80 120 200 165 60    4B 80120 200 70 60    5A 40 120 240 55 50    5B 40 120 240 85 50 6 98 120 21890 54.2 7 18.7 0 18.7 30 0 8 21.3 0 21.3 105 0 9 25.6 0 25.6 178 0 10 As required <30

The predicted energy input (in the form of 125 psig steam) fed viastream 12, is 557 Btu/lb water evaporated. This contrasts favorably tosimple evaporation efficiency [about 1000 Btu/lb]. At the same time, thefacility is predicted to be relatively inexpensive to construct andoperate, as will be evidence to persons of ordinary skill in the art onreview of the schematic.

Turning now to FIG. 5 same will be understood to show in schematic forman ethanol production facility and will be seen to include:

-   -   as corn milling facility 66, a cooking/liquefaction facility 68        and a saccharification facility 70; these are all substantially        conventional, in that they take corn and create therefrom a        feedstock suitable for fermentation;    -   a yeast conditioning facility 72, for producing a flow of water,        enzymes and yeast;    -   a continuous stirred tank reactor (CSTR) 76: to which the        fedstock, water, etc., are fed, in which fermentation        continuously takes place and from which a bleed stream 115 is        drawn;    -   a SAM device 70, coupled to the CSTR to: withdraw a flow of the        fermentation broth on a continuous basis, preferentially remove        alcohol from the withdrawn broth to produce an enriched alcohol        (brine) flow 104 and a remainder flow 131; and return the        remainder flow 131 to the CSTR 76;    -   a batch tank 78, which receives and ferments the bleed stream        135 in hatches    -   a second SAM device 20 coupled to receive the product from the        batch tank 78 and produce (i) a stream of whole stillage from        which ethanol has been substantially removed and (ii) brine        enriched in ethanol    -   a stillage processor 79    -   a secondary absorber 46, for absorbing the remainder of the        absorbables not taken up by the SAM devices 20;    -   a vent scrubber 74 for extracting trace alcohol from, inter        alia, the batch tank 78 and the secondary absorber 46 and        diverting same back to the cooking facility 68, before        exhausting non-condensables to atmosphere via stream 142    -   3 desorbers 84,82,80, arranged to create a three-stage desorber,        to regenerate the brine, produce a concentrated ethanol stream;        and produce a recycle water stream;    -   a condenser 90 and receiver 92, for condensing the recycle water        stream and returning same to the corn milling facility 68;    -   a rectifier/dehydration facility 86;    -   economizers 60 and pumps 64, for passing flows between the        various elements; and    -   ethanol product storage facility 88.

Predicted operating conditions for various of the flows are indicated inTable 2.

FERMENTATION TRAIN Stream Mass flow rate lb/hr percent percentTemperature Stream name # water sugars DGS ethanol total ethanol sugarsDegrees C. Mash fed to main fermentor 137 224,400 66,000 37,620 0328,020 0 20 30 Beer feed to SAM1 132 211,455 5,610 37,620 18,117272,802 7 2 30 Beer recycled from SAM1 131 198,511 5,610 37,620 6,039247,780 2 2 28 Main fermentor bleed 135 211,455 5,610 37,620 18,117272,802 7 2 30 Fully fermented beer 136 211,455 0 37,620 20,922 269,9978 0 32 BRINE TRAIN Stream Mass flow rate lb/hr Stream CompositionTemperature Stream name # LiBr Water Ethanol Total % LiBr % Water %Ethanol Degrees C. SAM1 vapours  99a 0 12,944.63 12,078.00 25,022.63 051.73 48.27 30 SAM2 vapours  99b 0 19,927.34 20,922.00 40,849.34 0 48.7851.22 30 Feed to Secondary Absorber 100 133,028 121,558 33,000 287,58650 42 11.47 55 Product from Secondary Absorber 101 133,028 128,78733,803 295,618 45 44 11.43 45 Strong Brine to SAM1 103 66,514 44,343 0110,857 60 40 0 70 Strong Brine to SAM2 104 66,514 44,343 0 110,857 6040 0 70 Low Pressure Desorber Product 107 133,028 88,686 0 221,714 60 400 95 High Pressure Desorber Poduct 112 133,028 105,799 3,426 242,254 5544 1.41 260 Mid Pressure Desorber Product 113 133,028 118,271 15,898267,197 50 44 6 175 Ethanol Laden Condensate 117 0 12,472 12,472 24,9440 50 50 202 Mid Pressure Vapor 118 0 10,516 17,905 28,421 0 37 63 138Ethanol Product as vapor 163 0 134 33,000 33,134 0 0 100 ambient

Persons of ordinary skill in the art will readily understand theoperation of the device in consideration of the flows and the schematic.Accordingly, for brevity, a detailed item-by-item description is neitherrequited nor provided.

However, Table 2 is notable at least for the following:

-   -   product streams fed to the rectifier 86 are of concentrations        suitable for conventional processing by pervaporation or        molecular sieve techniques;    -   calculations suggest that high quality heat requirements, i.e.,        fuel-generated heat, for the high pressure desorber 84, are        4,717 btu/gallon ethanol produced [up to the rectifier 86], this        contrasts favorably to common ethanol production facilities,        wherein heat requirements up to rectification can reach as high        as 18,000 btu/gallon    -   the broth withdrawn from CSTR 76 has a temperature of about        30° C. and the remainder broth has a temperature of about 28°        C.; this arrangement is advantageous, in that the broth is never        elevated in temperature above about 30° C. [or supercooled],        which would harm the live yeast.

Again, the facility is predicted to be relatively inexpensive toconstruct, as will be evident to persons of ordinary skill.

Without intending to be bound by theory, it is believed that theadvantageous energy and construction cost requirements flow in partfrom:

-   -   the pressure in the first volume 34 and the temperature of the        mixed liquid entering the first volume 32 are such that        substantially all of the heat transferred to the first volume 32        results in evaporation of the mixed liquid;    -   the remainder broth has a temperature lower than that of the        withdrawn broth, thereby reducing chilling loads on the CSTR;    -   the use of multiple-effect desorption; and    -   the relatively modest refrigeration loads associated with the        vaporization [which, in areas where very cold cooling water is        not available in abundance, i.e., as is commonly the case, must        be provided by mechanical means]

FIG. 6 shows a simplified variation of the FIG. 5 structure, withfurther detail in respect of an advantageous method for stillageprocessing, utilizing a SAM according to the invention.

Briefly, CSTR 76 receives feedstocks 96 and produces strong beer 98which is fed to a SAM apparatus 20. Weak beer 100 passes back from thisSAM to CSTR 76. A bleed stream 104 passes to batch tank 78. Strong beer102 from batch tank 78 is fed to its own SAM 20. Whole stillage 108 frombatch tank 78 is centrifuged 110 to produce wet cake 112 and thinstillage 114, the latter being sent to yet another SAM 20, to producesyrup 116 which, along with cake 112, is dried in a DDGS dryer 118.Dilute brine 120 produced by each of the SAMS is fed to still 94 forregeneration. Although still 94 shows all of the diluted brinesconverging, it should be understood that still apparatus 94 could havetwo trains, thereby to keep separate brine streams relatively higherconcentration in ethanol and brine streams relatively barren of ethanol.

The predicted utility in respect of the aforementioned propheticexamples has been verified experimentally.

Experimental Results

Twenty heat pipes, each 7.0″ in length and 0.25″ in diameter, weremounted horizontally, one above the other, to form an array about 10.0″in height. This assembly was sandwiched between transparent sheets ofacrylic. Two separate, side-by-side chambers [an evaporator chamber andan absorber chamber] were formed between the sheets, with the heat pipespassing through both chamber. A 0.5″ ID hose was used to connect the toppart of the evaporator chamber to the bottom of the absorber chamber. Atthe top of each chamber, a crude liquid distributor was provided. At thetop of each chamber, a 2 liter flask, vented to atmosphere was provided,and coupled to the liquid distributor of that chamber via a flow controlvalve. At the bottom of each chamber, a liquid exit port was provided,coupled to a collection flask. A vent at the top of the absorber chamberwas coupled a standard laboratory vacuum pump with two lines of defenseprotecting it from water and ethanol vapours.

The first defense measure was a secondary absorber comprised of a flaskpartly filled with a strong cool LiBr solution. Gases en route to thevacuum pump were forced to bubble through the solution in the flask,stripping them of absorbable components. The second stage of defense wasa liquid nitrogen cold trap.

Two runs were made. In each run, measured amounts of brine were providedin the bubbler tank and absorber-coupled flask and a measured amount ofbeer was provided in the evaporator-coupled flask; the flow controlvalves were opened; and temperature and pressure measurements were madeas the liquids traversed the unit. Readings were terminated when one orboth of the feed flasks had been drained.

TABLE 3 Run 1 Time Beer Beer Brine Brine System Elapsed Input OutputInput Output Pressure (min) ° C. ° C. ° C. ° C. mmHg 1 26 24 49 23 41.72 27 27 60 42 37.2 3 27 27 62 48 33 4 27 27 63 52 29.1 5 27 27 64 5227.7 6 27 28 64 55 27.7 7 27 29 65 53 28.6 8 27 31 66 56 28

Bubbler starting weight 1303 g ending weight 1304 g Cold trap startingweight 0 Ending weight 0 Beer starting weight 83 g ethanol + 952 g water= 1035 g (8% EtOH) ending weight 70 g ethanol + 931 g water = 1000 g (7%EtOH) Brine starting weight 701 g water + 1052 g LiBr = 1753 g (60%LiBr) Ending weight 13 g ethanol + 713 g H₂0 + 1052 LiBr = 1778 (59%LiBr)

This test confirmed that the SAM can preferentially remove ethanol froman ethanol-water mixture and simultaneously cool the ethanol watermixture. It also indicated that a secondary absorber is a useful way toremove residual water and ethanol vapors from the vacuum train. The heattransfer coefficient for the device in this ran was calculated as 33BTU/hr/ft²/° F.

TABLE 4 Run 2 Time Beer Beer Brine Brine System Elapsed Input OutputInput Output Pressure (min) ° C. ° C. ° C. ° C. mmHg 1 35 22 50 37 20 236 25 63 44 25 3 36 27 68 49 25 4 36 27 69 52 30 5 36 27 71 53 30 6 3730 72 55 30 7 37 30 72 55 40 8 36 30 72 54 42 9 37 31 72 53 40 10 37 3172 53 40 11 37 31 73 53 40 12 36 31 73 52 40 13 36 32 73 53 40 14 36 3376 58 40 15 36 33 77 60 45 16 35 34 78 61 43 17 34 34 78 63 43 18 34 3479 64 45

Bubbler starting weight 1303 g ending weight 1304 g Cold trap startingweight 0 Ending weight 16.5 g ethanol + 16.5 g water = 33 g (50% EtOH)Beer starting weight 481 g ethanol + 1236 g water = 1717 (28% EtOH)ending weight 307 g ethanol + 1154 g water = 1462 g (21% EtOH) Brinestarting weight 1239 g water + 1859 LiBr = 3098 g (60% LiBr) Endingweight 115 g EtOH + 1293 g H₂O + 1859 g LiBr = 3267 (43% LiBr)

This test also confirmed that the SAM device can preferentially removeethanol from an ethanol-water mixture and simultaneously coot theethanol water mixture. The heat transfer coefficient for the device inthis run was calculated as 70 BTU/hr/ft²/° F. As the liquid distributionsystem in the test apparatus left unwetted much of the heat pipe surfacearea, this performance is viewed as relatively favourable. A morethorough liquid distribution can be expected to bring the coefficient inline with published values for commercial systems, which typicallyexceed 150 BTU/hr/ft²/° F.

Whereas FIG. 1 shows a schematic SAM, it will be evident to persons ofordinary skill in the art that changes can be made.

FIG. 7 shows one such possibility, namely, an arrangement wherein theheat pipes 26 are arranged parallel to a common axis X-X and thestructure is adapted for pivotal movement about a horizontal axis Y-Ywhich is orientated normally to the common axis. It is contemplated thatthis arrangement could be used to periodically expedite clearance ofliquid from the heat-delivering parts of the pipes.

FIG. 8 shows another possibility, wherein the first volume 32 is definedby one or more first voids 32A, the second volume 34 is defined by oneor more second voids 34A, each of the one or more first voids 32A andeach of the one or more second voids 34A are defined by a respectivevessel 130; and piping 132 defines the vapor passage 36. It iscontemplated that this embodiment may have some usefulness in terms ofreduced construction costs, as well as heat transfer efficiency [shorterheat pipes are normally better]. Discrete vessels render it possible tocreate substantial pressure differentials between the absorption andvaporization operations, and commensurate greater temperaturedifferentials. A greater temperature differential would result in higherheat transfer through the heat pipes; this could have advantage in termsof capital costs, i.e. fewer heat pipes and smaller vessels.

However, it should be understood that small pressure differentials couldbe created even within a SAM device of the type shown schematically inFIG. 1, by the interposition, for example, of a pump or fan in the vaporpassage.

FIG. 9 shows yet another possible SAM structure, wherein the vessel 21is defined by a horizontally-orientated cylindrical vessel, the vaporpassage 35 [indicated by arrows A] is defined by external piping (notshown) and the first volume 32 and second volume 34 are separated fromone another by a vertical bifurcating wall 140. The wall is defined byupper 142 and lower 144 ridges extending interiorly from the tubularwall of the vessel 21. A rubber 148 sheet spans between the ridges 142and 144 and is sandwiched between steel sheets 146 and 150 which aresecured to one another by upper 156 and 152 lower webs. The rubber sheet148 is perforated with holes to permit the heat pipes 26 to be passedtherethrough in substantially hermetically sealed relation; the steelsheets 146,150 have corresponding holes, of larger diameter, to permitfree passage of the heat pipes. Without intending to be bound by theory,this arrangement is believed to be advantageous from the standpoint ofrelatively low construction costs and simplicity in terms ofmaintenance; for maintenance, the operator would merely be required toremove one end of the vessel, and slide the entire heat pipe assemblyout horizontally. Various bearings or rollers (not shown), could also beemployed, if desired, to further simply construction. Further, whereas asingle bifurcating wall is shown, the vessel could be segmented by twowalls, each having heat pipes formed therethrough, to produce astructure having similar functionality to that shown in FIG. 8. In thistwo wall embodiment (not shown) the heat pipes could be angled, so thatdrop flow could travel back and forth in the chamber.

Further, whereas specific operating conditions are delineated in thedescription relating to FIGS. 4 and 5, it will be understood that widevariations are possible.

For example, in the context of an ethanol production facility, whereinthe viability of the yeast is to be maintained on a continuousfermentation basis, at least the following ranges are contemplated tohave utility:

-   -   the broth withdrawn from the fermentation arrangement can have a        temperature of about 28-32° C. and an ethanol concentration of        about 4-10%;    -   the remainder broth can have a temperature of about 2-4° C.        lower than that of the withdrawn broth and have an ethanol        concentration of about 2-4% less than that of the withdrawn        broth; and    -   the pressure in the first volume can be about 30-100 Torr.

As well, whereas the structure of FIG. 5 is indicated to be useful forethanol production, persons of ordinary skill in the art will readilyrecognize that the structure could be readily modified for handlingother separations, notably but not limited to butanol and methanol.Indeed, the general structure of FIG. 5 could be useful for anycatabolic reaction having a catabolic inhibitor capable of removal byabsorption. Further, whereas the description references continuousproduction, it should be understood that this is not strictly necessary.In a batch ethanol operation, broth could be withdrawn from the batchtank while the fermentation is underway and passed through a SAM device,to withdraw ethanol. Removing ethanol from the batch would take stressoff the yeast and could decrease cycle time and increase yield. As well,whereas in the context of ethanol and a LiBr brine, the thermodynamicsare such that ethanol is withdrawn preferentially, i.e. at a higherconcentration than the bulk, this is not strictly required forusefulness. In the context of an aqueous system, for example, whereinwater and another component are being withdrawn, there could beoccasions where it was acceptable that water was withdrawn in preferenceto the other component, and make-up water was added to balance flows. Inthis further regard, it should be understood that in this specificationand the appended claims, ‘liquid mixture’ means a liquid with anothermaterial mixed together, the other material may be liquid, such asalcohol, but this is not necessarily the case, as evidenced from, interalia, the apple juice concentrator example.

Further, whereas the secondary absorbers are shown in series with theSAM devices, it will be appreciated that this is not necessary.Secondary absorbers could be deployed in parallel, or omitted altogetherin some situations.

Additionally, whereas the distributors are illustrated schematically asperforated pipes, but it will be understood that sprayers ordistribution trays, such as used in packed columns, could be used. Theparticular form of distributor chosen will vary, inter alia, with thegeometry of the reactor and is a matter of routine for persons ofordinary skill.

As yet another option, not shown, the structure of FIG. 5 could usefullybe used as an adjunct to a conventional dry-mill corn ethanol plant. Inplants of this type, the bottoms of the beer columns are typically sentto centrifuges, for the production of DDGS and other co-products. Thesebottoms contain unfermented C5 and C6 fermentable sugars, primarilycellulose and hemi-cellulose, which are difficult to process. Diversionof this bottoms stream to the structure of FIG. 5, for pre-treatment,hydrolization and fermentation, allows additional ethanol to beextracted from the original can feedstock, and this incremental ethanolproduction is carried out in circumstances that obtain the generalbenefits in energy efficiency previously mentioned. Without intending tobe bound by theory, it is believed that this modification to an existingplant in this way can increase ethanol yield per bushel of corn; on aper bushel of corn basis, increase revenue from ethanol sales thatsubstantially offset losses in revenue from decreased sales of DDGS andother co-products; increase production capacity of the main plant (inthat fermentation residence time can be reduced in the main plant, sinceunfermented sugars will be captured in the add-on plant); and generallyincrease revenues that offset increases in costs.

As another option, the SAM device could be replaced with a conventionalliquid-liquid heat exchanger. FIG. 10 shows a tube 204 and shell 202heat exchanger configured for this purpose. In this case, the flow ofmixed liquid 242 would enter a manifold 206 on one side of the heatexchanger and travel through tubes 204 to manifold 208. During thistravel, the mixed liquid, would be partially vaporized into a flow ofvapor 230 and a depleted flow of liquid 234. The flow of vapor 230 isdirected back into the shell 202, at 232. An entrainment separator 210ensures that only vapor is directed to the shell 202. Strong brine 226is introduced into the shell such that vapor 232 is introduced to thebrine 226. Absorption of the vapor 232 occurs, as in the case of theearlier-described embodiments, producing a brine enriched in ethanolwhich exits the shell at 228. Gases 236 leaving the shell pass to anentrainment separator 222, to return any entrained brine to the shell at238, and a vacuum pump 224 draws non-condensables from the shell to exitat 240. A blower 220 is used to create a pressure differential in thevapor flows between 230 and 232, to account for pressure drop in thesystem. This alternative could have some advantage in terms of capitalcosts. However, the vapor 230 is in substantial vapor-liquid equilibriumwith the depleted flow 234, i.e. higher water content, which hasdisadvantage in terms of operating costs.

Yet further variations on all the above would be readily appreciated bypersons of ordinary skill in the art. Accordingly, the invention shouldbe understood as limited only by the accompanying claims, purposivelyconstrued.

The invention claimed is:
 1. Process for use with a flow of a liquidmixture that is separable by vaporization into a flow of vapor and adepleted flow of liquid, the process comprising: a vaporization step,wherein a portion of said liquid mixture flow is vaporized to producesaid flow of vapor and said depleted flow of liquid; an absorption step,wherein (i) the flow of vapor is introduced to a flow of brine which isadapted to exothermically absorb one or more components from the vaporand (ii) heat is withdrawn, to produce at least a flow of heat and aflow of brine which is enriched in the one or more components; and aheat transfer step, wherein the heat withdrawn in the absorption step istransferred, to drive the vaporization in the vaporization step, whereinthe transfer of heat to drive the vaporization is associated with thephase change of a working fluid from a gaseous state into a liquidstate; the withdrawal of heat in the absorption step involves the phasechange of the working fluid from the liquid state into the gaseousstate; in the liquid state, the working fluid flows only by one or moreof gravity, convection and wicking; and in the gaseous state, theworking fluid flows only by one or more of diffusion and convection. 2.A process according to claim 1, wherein one or more heat pipes are usedto withdraw the heat for the absorption and to drive the vaporization.3. A process according to claim 2, wherein the one or more heat pipesare stacked such that the one or more heat pipes operate in use as apacked vaporization column in the vaporization and as a packedabsorption column in the course of vaporization.
 4. A process accordingto claim 1, wherein the flow of vapor is in substantial vapor-liquidequilibrium with the liquid mixture.
 5. A process according to claim 1,wherein, in use, the temperature of the depleted flow of liquid is lowerthan the temperature of the liquid mixture.
 6. A process according toclaim 1, wherein substantially all of the heat withdrawn from theabsorption results in vaporization.